Due to the advantages of high surface areas, large pore volumes and pore sizes, abundant nitrogen content that favored the metal-support interactions, N-doped ordered mesoporous carbons are regarded as a kind ...Due to the advantages of high surface areas, large pore volumes and pore sizes, abundant nitrogen content that favored the metal-support interactions, N-doped ordered mesoporous carbons are regarded as a kind of fascinating and potential support for the synthesis of effective supported cat-alysts. Here, a N-doped ordered mesoporous carbon with a high N content （9.58 wt%）, high surface area （417 m^2/g）, and three-dimensional cubic structure was synthesized successfully and used as an effective support for immobilizing Pt nanoparticles （NPs）. The positive effects of nitrogen on the metal particle size enabled ultrasmall Pt NPs （about 1.0 ± 0.5 nm） to be obtained. Moreover, most of the Pt NPs are homogeneously dispersed in the mesoporous channels. However, using the ordered mesoporous carbon without nitrogen as support, the particles were larger （4.4 ± 1.7 nm） and many Pt NPs were distributed on the external surface, demonstrating the important role of the nitrogen species. The obtained N-doped ordered mesoporous material supported catalyst showed excellent catalytic activity （conversion 100%） and selectivity （〉99%） in the hydrogenation of halogenated nitrobenzenes under mild conditions. These values are much higher than those achieved using a commercial Pt/C catalyst （conversion 89% and selectivity 90%）. This outstanding catalytic perfor-mance can be attributed to the synergetic effects of the mesoporous structure, N-functionalized support, and stabilized ultrasmall Pt NPs. Moreover, such supported catalyst also showed excellent catalytic performance in the hydrogenation of other halogenated nitrobenzenes and nitroarenes. In addition, the stability of the multifunctional catalyst was excellent and it could be reused more than 10 times without significant losses of activity and selectivity. Our results conclusively show that a N-doped carbon support enable the formation of ultrafine metal NPs and improve the reaction ac-tivity and selectivity.展开更多
Although polymer electrolyte membrane fuel cells （PEMFCs） have received broad attention due to their virtually zero emission, high power density, and high efficiency, at present the limited stability of the electroc...Although polymer electrolyte membrane fuel cells （PEMFCs） have received broad attention due to their virtually zero emission, high power density, and high efficiency, at present the limited stability of the electrocatalysts used in PEMFCs is a critical limitation to their large-scale commercialization. As a type of popularly used electrocatalyst material, carbon black supported platinum （Pt/C）--although highly efficient--undergoes corrosion of carbon, Pt dissolution, Ostwald ripening, and aggregation of Pt nanoparticles （NPs） under harsh chemical and electro- chemical oxidation conditions, which results in performance degradation of the electrocatalysts. In order to overcome these disadvantages, many groups have tried to improve the carbon support materials on which Pt is loaded. It has been found that some novel carbon nanomaterials and noncarbon materials with high surface areas, sufficient anchoring sites, high electrical conductivities, and high oxidation resistance under the strongly oxidizing condition in PEMFCs are ideal alternative supports. This review highlights the following aspects： （i） Recent advances in using novel carbon nanomaterials and noncarbon support materials to enhance the long-term durability of electrocatalysts; （ii） solutions to improve the electrical conductivity, surface area, and the strong interaction between metal and supports; and （iii） the synergistic effects in hybrid supports which help improve the stability of electrocatalysts.展开更多
基金supported by the National Natural Science Foundation of China(201573136,U1510105)the Scientific Research Start-up Funds of Shanxi University(RSC723)~~
文摘Due to the advantages of high surface areas, large pore volumes and pore sizes, abundant nitrogen content that favored the metal-support interactions, N-doped ordered mesoporous carbons are regarded as a kind of fascinating and potential support for the synthesis of effective supported cat-alysts. Here, a N-doped ordered mesoporous carbon with a high N content （9.58 wt%）, high surface area （417 m^2/g）, and three-dimensional cubic structure was synthesized successfully and used as an effective support for immobilizing Pt nanoparticles （NPs）. The positive effects of nitrogen on the metal particle size enabled ultrasmall Pt NPs （about 1.0 ± 0.5 nm） to be obtained. Moreover, most of the Pt NPs are homogeneously dispersed in the mesoporous channels. However, using the ordered mesoporous carbon without nitrogen as support, the particles were larger （4.4 ± 1.7 nm） and many Pt NPs were distributed on the external surface, demonstrating the important role of the nitrogen species. The obtained N-doped ordered mesoporous material supported catalyst showed excellent catalytic activity （conversion 100%） and selectivity （〉99%） in the hydrogenation of halogenated nitrobenzenes under mild conditions. These values are much higher than those achieved using a commercial Pt/C catalyst （conversion 89% and selectivity 90%）. This outstanding catalytic perfor-mance can be attributed to the synergetic effects of the mesoporous structure, N-functionalized support, and stabilized ultrasmall Pt NPs. Moreover, such supported catalyst also showed excellent catalytic performance in the hydrogenation of other halogenated nitrobenzenes and nitroarenes. In addition, the stability of the multifunctional catalyst was excellent and it could be reused more than 10 times without significant losses of activity and selectivity. Our results conclusively show that a N-doped carbon support enable the formation of ultrafine metal NPs and improve the reaction ac-tivity and selectivity.
文摘Although polymer electrolyte membrane fuel cells （PEMFCs） have received broad attention due to their virtually zero emission, high power density, and high efficiency, at present the limited stability of the electrocatalysts used in PEMFCs is a critical limitation to their large-scale commercialization. As a type of popularly used electrocatalyst material, carbon black supported platinum （Pt/C）--although highly efficient--undergoes corrosion of carbon, Pt dissolution, Ostwald ripening, and aggregation of Pt nanoparticles （NPs） under harsh chemical and electro- chemical oxidation conditions, which results in performance degradation of the electrocatalysts. In order to overcome these disadvantages, many groups have tried to improve the carbon support materials on which Pt is loaded. It has been found that some novel carbon nanomaterials and noncarbon materials with high surface areas, sufficient anchoring sites, high electrical conductivities, and high oxidation resistance under the strongly oxidizing condition in PEMFCs are ideal alternative supports. This review highlights the following aspects： （i） Recent advances in using novel carbon nanomaterials and noncarbon support materials to enhance the long-term durability of electrocatalysts; （ii） solutions to improve the electrical conductivity, surface area, and the strong interaction between metal and supports; and （iii） the synergistic effects in hybrid supports which help improve the stability of electrocatalysts.
